Circuit Description
WARNING: This page is about a different car, the 2003 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.
Knock sensors are located under intake manifolds, on inside of cylinder block. Knock sensors generate voltage when engine block vibrates due to knocking. If engine knocks, ECM will retard ignition timing. If DTC is set, ECM will operate in fail-safe mode (maximum timing retardation). See Fig 1. DTC is set when there is no knock sensor signal to ECM with engine speed of 1700-5400 RPM. Possible causes are:
- Open or short in knock sensor circuit.
- Knock sensor (loose).
- Faulty ECM.